Old Rappahannock Co., VA
History
There is an Old Rappahannock and a modern Rappahannock created in 1833. The old county was split in 1692 into Essex and Richmond. Essex subsumed South Farnham Parish, a part of Sittenburne Parish and St. Mary's Parish. North Farnham Parish fell wholly into Richmond County.For convenience, the state decided that records belonging to the old Rappahannock County would be maintained in Essex County. Note that Old Rappahannock County was originally formed from Lancaster County and records before 1651 are in Lancaster County.
Source: "The Formation of Essex County", Essex County Historical Society, http://www.essexmuseum.org/archive/bulletin-vol-02-5-1972.pdf.